Plants such as thermal power plants and nuclear power plants utilize systems for swiftly detecting device abnormalities and maintaining device to ensure the safe operation of device within the plant. In these types of systems, sensors are installed in each device in order to detect indications of abnormal device or indications that might lead to abnormal device, and the systems collect physical amounts (hereafter, “quantities”) measured by the sensors and by diagnose these accumulated physical quantities to diagnose abnormalities in each piece of device.
These device abnormalities can be diagnosed by establishing rules in advance that show what calculation formula to utilize for the measured physical quantity. The rules established for this type of diagnosis are sometimes generated by applying calculation formulas utilized in similar device structures in similar systems.
Japanese Unexamined Patent Application Publication No. 2007-094538 discloses for instance, an airport light maintenance system that extracts failure histories containing similar peripheral information when a failure has for example been found in the lights within an airport facility; and estimates the cause of the failure by comparing past failure histories with peripheral information on the environment (temperature, rainfall amount) where the failure occurred, the number of replacements of failed lights, the number of sub-stations, power cable total extension lengths between main station and sub-stations, and identical airports and identical type circuits.
The International Patent Publication No. WO03/055145 pamphlet discloses technology for estimating the cause of failure when a failure has been found in a communication path where a plurality of relay devices are coupled in numerous stages, by searching the failure histories of communication paths having a connecting structure similar to that (problem) communication path.